Grid machine and method of controlling grid bows



Oct. 24, 1939. c, NARWID 2,176,918

GRID MACHINE AND METHOD OF CONTROLLING 'GRID BOWS Original Filed Dec. 28, 1937 2 Sheets-Sheet' l A TTORNEYS.

Oct. 24, 1939, Q w g 2,176,918

GRID MACHINE AND METHOD OF CONTROLLING GRID BOWS Original Filed Dec. 28, 1937 2 Sheets-Sheet 2 IINVENTOR. Cj/pr-l'aiv 14. A OPW/b ATTORNEYS.

Patented Oct. 24, 1939 PATENT OFFICE GRID MACHINE AND METHOD OF CONTROL- LING GRID BOWS Cyprian A. Narwid, Harrison, N. J., assignor to Tung-Sol Lamp Works Inc., Newark, N. J., a corporation of Delaware Application December 28, 1937, Serial No. 182,043

. I Renewed June 28, 1939 8 Claims.

This invention relates to machines for making grids'for use in radio tubes and the like and method of preventing or controlling the bows or bends usually present in such grids.

Grids for use in radio tubes and the like are usually manufactured by notching support wires carried by a relatively rotating mandrel, winding the grid wire. into the notches and fastening the gridwire intothe notches, as by swaging. The support wires after the notching, winding and swaging operations of conventional practice tend to bend or depart from a perfectly straight position with the result that undesirable bows or bends are formed in the finished grids.

' One object of the invention is tocontrol the degree of the bow or bend in either direction of the support wires so as to avoidthe undesirable bends or bows of the prior practice and to obtain grids approaching the straight or unbent character desired in practice.

Other objects of the invention will hereinafter appear.

For a better understanding of the invention reference may be had to 'the accompanying drawings forming a part'of this application wherein:

Fig. 1 is a side elevational view partly in section' of the essential mechanism of a grid machine embodying the invention;

Fig. 2 is an end view of parts thereof;

Fig.3 is a view indicating the undesirable bend or bow of the grid of conventional practice and Fig. 4 illustrates the character of the grid which may be'obtained according to the present invention. 7

Referring to the drawings, there is shown a grid machine embodying the conventional notch ing wheel I carried in asuitable frame 2, a conventional swaging wheel 3 suitably supported by a frame 4, a conventional spindle mounted in 4 bearings 6 and carrying a mandrel I, supply reels 8 for supplying support wires 9 to the mandrel grooves I, a reel It for supplying the grid wire II and a clamping head I2 for drawing the support wires 9 along the grooves I of the mandrel 1.

These mechanisms operate as in conventional practice to draw the support wires 9 from the reels 8 through the machine and as these support wires are drawn through the notching wheel I 50 forms the notches indicated in the support wires 9 for the reception of the turns of wire I I. After the positioning of the wire in a notch, the swaging wheel 3 fastens the grid wire firmly to the support wires by the usual swaging operation, and as indicated in dotted lines in Fig. 1 the swager 3 is movable toward and away from the mandrel I (by a mechanism omitted for convenience in illustration) for the purpose of discontinuing at desired intervals the swaging operations, these intervals of non-swaging being those portions of the grid where the same are severed into the required grid lengths for use in radio tubes and the like. The mandrel I and clamping head I2 on the one hand and the notching wheel I and swaging wheel 3 on the other are relatively rotatable, and in the particular embodiment shown the mandrel I is carried by the rotating spindle 5 (with which rotate the reels 8) while the notching wheel I and swaging wheel 3 are relatively fixed, though the wheels I and 3 are journaled for rotation or oscillation about their axes and are adjustable toward and away from the mandrel. As the mandrel I is rotated, that part of the support wires which projects above the grooves I in the mandrel I are engaged by the notching wheel I to form the notches and similarly the swaging wheel engages the support wires at the notches to swage the grid wire I I into fixed position on the supports.

In the production of the grids according to the conventional practice the support wires 9 tend to bend towards the notched side with the resultant bow formed in the grid as indicated, slightly exaggerated, in Fig. 3. This renders the grid difficult to mount and assemble and the degree of bow or bend of the grid support wires in conventional practice cannot be predetermined with any certainty.

I have discovered that this bend or bow of the support wires may be prevented or controlled by applying sufficient pressure, radially directed, against the support wires 9 while disposed in the grooves of the mandrel and at points slightly in advance of the notching wheel I. This pressure may be exerted in any suitable manner and according to the embodiment of the invention herein illustrated I have shown a pressure applying attachment comprising a collar I5 bored to fit over the grid mandrel I and rigidly fastened thereto to rotate therewith. This collar I5 is provided with slots on the opposite sides thereof and in the plane of the guide grooves formed in the mandrel I for the reception of lever arms I6. These arms I6 are journalled in these slots on the pins Il as fulcrum points, and on the ends proj ecting toward the notching wheel I are provided mounted pressure rollers I8 for engaging the support wires 9 in advance of the notching wheel I and swaging wheel 3, these rollers I8 being journalled in slots or forks formed in the ends of the lever arms H1. The projecting ends of the lever arms I6 on the opposite sides of the pin I! are provided with adjusting screws l9 which are screw threadedly attached respectively thereto and whose inner ends !9 engage the mandrel l, the groove in the mandrel at this point being deep enough to enable the adjusting screws I9 to engage the mandrel without binding against the support wires 9. The depth of the groove 1 decreases at 25 to a point where the support wires 9 project above the mandrel sofas to be engaged by the rollers IS, the notching wheel I and the swaging wheel 3. By the adjustment of the screws l9 any pressure desired may be placed upon the support wires 9 at the points of engagement with the rollers !8. At 20 are indicated clamping screws fastened to the rearwardly projecting ends of the lever arms H3 at right angles to the adjusting screws l9, and these clamping screws 20 are used for locking and retaining the adjusting screws l9 in their adjusted position after proper adjustment has been made. Any degree of pressure, and of an unyielding character, may thereby be applied to the support wires 9 and the support wires 9 are rigidly held against the bottom of the grooves. By adjusting the pressure the bend or bow of the grid support wires 9, indicated in Fig. 3, may be substantially obviated to provide a grid asshown in Fig. 4 with perfectly straight support wires. The pressure exerted must be considerable to effect this result and while this pressure may be varied within limits to control the bowing or bending I have found that there is a critical adjustment for obtaining the straight grids of Fig. 4.

I claim:

1. In a grid machine of the character set forth a mandreLmeans for feeding support wires therealong, notching means for forming notches in the support wire, said notching means and mandrel being relatively rotatable, means for supplying grid wire to the notches and means for applying unyielding pressure'to the support wires at points slightly in advance of the notching means, said pressure applying means comprising lever elements pivotally mounted onthe mandrel, with pressure applying rollers carried by ends of said lever elements projecting toward the notching means and pressure adjusting screws carried by the other ends of the lever elements and engaging the mandrel.

2. In a machine of the character set forth in claim 1 wherein the mandrel is provided with grooves on the opposite sides thereof for guiding and supporting the support wires and said lever elements are fulcrumed on an axis at right angles to the plane of the grooves.-

am ne 3. In a grid machine of the character set forth, a relatively rotatable mandrel and notching means, means for feeding support wire along the mandrel and for feeding grid wire to the notches formed by the notching means, and non-yielding means fixed. with respect to the mandrel for exerting pressure against the support wire in a direction radially of the mandrel and at a point in advance of the notching means.

4. In a grid machine of the character set forth,

a relatively rotatable mandrel and notching means, means for feeding support wire along the mandrel and for feeding grid wire to the notches formed by the notching means, and means for exerting pressure against the support wire in a direction radially of the mandrel and at a point in advance of the notching means, the means for exerting pressure on the support wires including adjustable rollers engaging the relatively moving support wires.

5. In a grid machine of the character set forth, a relatively rotatable mandrel. and notching means, means for feeding support wire along the mandrel and for feeding grid wire to the notches formed by the notching means, and means for exerting pressure against the support wire in a direction radially of the mandrel and at a point in advance of the notching means, the means for exerting pressure upon the supporting wires comprising fulcrumed lever elements carrying on one end thereof pressure rollers in engagement with the support wires, and carrying on the other side of the fulcrums pressure adjusting screw elements and means for locking the screw elements in their adjusted position.

6. A machine of the character set forth in claim 3 comprising means for fastening the grid wire within the notches formed by the notching means.

'7. The method of making grids comprising support wires with grid wire coiled therearound and fastened thereto which consists in drawing the support wires over a mandrel and simultaneously therewith notching the wire, feeding "grid wire thereto and fastening thegrid wire to the'support wire, and also simultaneously therv'vith'continuously applying unyielding pressure'to the support wires at points in advance of" the notching operation.

8. A machine for making grids comprising means for coiling grid wire about support wire and fastening the'grid wire to the support wire, 

